The announcement came from Andre Birotte Jr., who said his office in Los Angeles "is closing an investigation into allegations of federal criminal conduct by members and associates of a professional bicycle racing team owned in part by Lance Armstrong."
Armstrong, a cancer survivor and a seven-time winner of the Tour de France, has faced allegations of drug use throughout his career. He was one of the most frequently tested athletes in all of sports and authorities never found evidence of drugs in his system.
Landis made his claims after having the 2006 Tour de France title taken away for drug use. Hamilton's statements came on the television news show "60 Minutes" last year.
The federal investigation has been ongoing for two years.
Armstrong issued a statement saying he was "gratified" the investigation has been concluded.
"It is the right decision and I commend them for reaching it," he said. "I look forward to continuing my life as a father, a competitor, and an advocate in the fight against cancer without this distraction."
In a statement, the U.S. Anti-Doping Agency said it will pursue its investigation into the use of banned substances, the Los Angeles Times reported.
"Unlike the U.S. Attorney, USADA's job is to protect clean sport rather than enforce specific criminal laws," the statement said. "Our investigation into doping in the sport of cycling is continuing and we look forward to obtaining the information developed during the federal investigation."
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